川西坳陷中江气田侏罗系沙溪庙组致密砂岩储层特征及主控因素分析

Reservoir Characteristics and the Main Controlling Factors on the Middle Jurassic Shaximiao Formation Tight Sandstone Reservoirs in the Zhongjiang Slope of Western Sichuan Depression

通过对中江气田沙溪庙组储层的岩石学、物性、储集空间类型、成岩作用等基本特征的研究,明确了本区储层形成的主控因素,建立了优质储层的地质模型,并据此预测出本区优质储层的分布。中江气田沙溪庙组岩石类型以岩屑长石砂岩和长石岩屑砂岩为主,具有富长石的特征。储层平均孔隙度为9.0%,平均渗透率为0.096 m D,属于低孔低渗致密砂岩储层。孔隙类型主要为剩余粒间孔和粒间溶孔,其次为粒内溶孔。储层总体表现出沉积-成岩控储的特征,有利储层的地质模型是:较粗粒度,高长石、低岩屑,低碳酸盐胶结物,不同地区不同层段优质储层的分布均有不同。

The reservoir characteristics and the impact of the main controlling factors on the Shaximiao formationof compact clastic reservoirs in the eastern slope of Chuan Xi dression are described based on petrologic, petro-physical analysis, porosity types and diagenesis. Reservoirs are composed of medium or fine grained lithic arkosesand feldspathic litharenites, and primary feldspar lithic sandstone. The reservoirs are characterized by low porosityand low permeability. The dominant type of porosity is surplus intergranular porosity and interparticle dissolutionpore. Depositional factor and various types of diagenetic alterations have caused considerable influence on thereservoir properties. The reservoir geological model is coarse-grained, high-feldspar, low rock debris, low carbon-ate cement. The high quality reservoir in Gaomiaozi - Fenggu area is mainly concentrated in the JS21, JS24 andJS33 sand groups, and JS11, JS12, JS14, JS22, JS31 sand groups in Zhongjiang - Huilong area.